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Silvicultural practices such as planting spacing are known to induce variation in wood quality, but the spatial variation of the wood traits along stems as a function of plantation density has been rarely reported, especially in fast-growing Eucalyptus plantations. Therefore, the objective of the present study was to generate a better understand about the effect of planting spacing on the variation of wood density, extractives and lignin content within Eucalyptus trees managed for pulp and paper industry. Four commercial clones planted in four planting spacing arrangements (3×1 m, 3×2 m, 3×3 m, and 3×4 m) were investigated at five-year-old. Wood discs (30 mm thick, defects free) were collected at six longitudinal points (base, 1.3 m from and at 25 %, 50 %, 75 % and 100 % of the commercial height) of the three Eucalyptus trees of each treatment, totaling 48 trees and 288 discs. Near infrared (NIR) models formerly calibrated for estimating wood density, extractive and lignin content were applied to NIR spectra collected radially at five equidistant points on the discs in order to estimate these wood properties along the tree trunks. The results revealed that the largest planting spacing arrangement (3×4 m) induced the formation of wood with greatest spatial variation, especially below 25 % of height. The spatial variation patterns vary according to genetic material. In terms of basic wood density, clone D exhibited the widest range of variation (52.7 kg m−3), whereas clone B showed the lowest values (39.6 kg m−3). Lignin content did not significantly differ between clones but varied significantly based on planting density. These results indicates that planting spacing affects the spatial variation in lignin content and wood density along the stem, depending on the genetic material. [Display omitted] • Radial variation in wood density and lignin content was smaller in narrow spacing. • Genetic material impacted wood density variation, mainly below 50 % of height. • Wood basic density varies more intensely within the tree than lignin. • Wood basic density increases with tree height for all planting spacings. • Lignin content do not vary between planting spacing and genetic material. [ABSTRACT FROM AUTHOR]

This study investigates the effects of press channel length on the quality of wood pellets, focusing on key aspects such as density, radial porosity distribution, and mechanical stability, both at the time of delivery and during storage. Wood pellets were produced using press channels with diameter-to-length (D/L) ratios of 1:3, 1:4, and 1:5 to evaluate how variations in die geometry influence pellet quality. Micro-computed tomography (μCT) analysis indicates that the D/L ratio of the press channel significantly impacts the porosity within the pellets. Short press channels are associated with great variability in the radial porosity distribution of the wood pellets, while longer press channels lead to uniformly low porosity over the radius. Furthermore, pellets produced with longer press channels exhibit a smoother surface with fewer cracks and greater resistance to structural degradation under varying humidity conditions. Although high-density pellets show improved mechanical strength and recovery potential in humid environments, remaining damage in the form of cracks and alterations in radial porosity distribution lead to reduced strength compared to their initial state. [Display omitted] • Wood pellets of differing quality are produced using press channels with various diameter-to-length ratios. • Radial porosity variations from micro computed tomography reveal key mechanisms affecting pellet quality. • Longer press channels produce wood pellets with consistently low radial porosity. • High-density pellets exhibit greater mechanical strength under humid conditions compared to low-density pellets. • High-density pellets demonstrate superior recovery potential when in a wet state. [ABSTRACT FROM AUTHOR]

Woody plants are important components of dryland ecosystems. Our understanding of wood decomposition in drylands, an important component of biogeochemical cycling, is poor compared to that in mesic ecosystems. To uncovering the complex interactive effects of the different key drivers, we studied the effects of precipitation, position (aboveground and belowground), wood size and litter quality of plant species (four to five local species and one widespread woody species) on woody litter decomposition rates along a precipitation gradient from 37 to 369 mm, spanning five dryland sites. Wood dry matter content (DMC) was a critical negative predictor of wood decomposition in water-limited ecosystems. Thicker woody litter had lower decomposition rates (k values) directly because of smaller relative surface exposure, and indirectly through higher wood DMC or lower bark mass ratio (bark mass divided by wood mass for a given branch length). Mean annual precipitation (MAP) increased the k values both directly, and indirectly by decreasing the wood DMC and increasing the bark mass ratio due to species turnover. The k values of buried woody litter were mostly two to three times higher than litter on the soil surface, but not different at the extremely arid site. A steeper slope of the relationship between overall woody litter quality (particularly wood DMC) or annual precipitation and k values was observed belowground than aboveground, as related to the higher moisture belowground than aboveground. These findings highlight the complex interactions among climate (precipitation), litter position, size and quality on wood decomposition in drylands, thereby helping to improve our mechanistic understanding of dryland woody litter decomposition. We conclude that wood decomposition at the regional and local scales will influence biogeochemical cycling in drylands under future climate change through both direct effects of moisture and indirect effects of litter quality characteristics. • Precipitation drives dryland wood decomposition directly and indirectly via wood litter quality. • Precipitation has a stronger effect on wood decomposition belowground than aboveground. • The wood quality effect on decomposition is stronger belowground than aboveground. • Carbon models should include interactions of climate, litter traits and locations. [ABSTRACT FROM AUTHOR]

Climate change and the advancement of forestry in areas with greater water scarcity represent major challenges for Eucalyptus cultivation in Brazil. This study aimed to evaluate the productivity and wood quality of non-traditional Corymbia and Eucalyptus species in two Brazilian climatic conditions, to expand the genetic base available for breeding programs. Mean annual increment, wood density, stem biomass, heartwood and bark percentage, tangential vessel diameter, vessel frequency, fiber length, and fiber wall thickness were assessed. Four Corymbia species (Corymbia citriodora subsp. citriodora , Corymbia henryi , Corymbia torelliana , Corymbia citriodora subsp. variegata) and three Eucalyptus species (Eucalyptus amplifolia , Eucalyptus longirostrata , Eucalyptus major) were evaluated. Monthly evaluations were conducted on the mean air temperature, precipitation, and soil water deficit. Soil water deficit had a negative impact on mean annual increment, biomass, and heartwood percentage, while also resulting in higher bark percentages. However, it did not affect wood density or vessel diameter. The species showed different behaviors in response to the increase in water deficit. Eucalyptus longirostrata had the lowest impact on the environment, the highest mean annual increment (48.40 m³ ha−1 and 26.94 m³ ha−1) and heartwood percentage values (19.23 % and 16.27 %). Corymbia henryi had the most similar mean annual increment values in both locations (25.33 m³ ha−1 and 20.18 m³ ha−1), but there was a significant decrease in heartwood formation in the location with the lower soil water deficit (18.20 %). Corymbia citriodora subsp. citriodora , Corymbia henryi , Corymbia citriodora subsp. variegata , Eucalyptus major , and Corymbia torelliana displayed strong growth and wood characteristics, indicating great potential for cultivation in both locations. • Site differences had an impact on tree growth. • Productivity decreases as water deficit increases. • The climate variations across sites didn't impact the species' vessel density or diameter. • C. citriodora subsp. variegata and E. longirostrata had the highest stem biomass values in both sites. [ABSTRACT FROM AUTHOR]

It is known that laccase genes are involved in lignin synthesis. Eucalyptus is an important timber species; functional studies of specific laccase members and their upstream regulatory factors in Eucalyptus are incomplete, and the mechanism of lignin content variation in polyploid plants remains unclear. Therefore, in this study, we investigated the function of EuLAC17 by overexpressing it in tobaccos and the result showed the lignin content in transgenic tobacco increased significantly. Further, yeast one hybrid sequencing was used to identify a series of potential regulatory factors of EuLAC17 , among which EuMYB308 showed the most significant correlation with EuLAC17. Yeast one hybrid, dual-luciferase reporter gene assay and electrophoretic mobility shift assay jointly verified that EuMYB308 could directly target the EuLAC17 promoter and repress its expression. In addition, overexpression of EuMYB308 resulted in significant reductions in plant growth, xylem cell lumen area, cell wall thickness and lignin content. Transcriptome sequencing showed that lignin biosynthesis genes including laccase genes were significantly differential expression in transgenic plants compared with wild-type plants. In triploid Eucalyptus urophylla , the expression of EuMYB308 was significantly upregulated, which may enhance the inhibition of EuLAC17 and thus reduce its expression level in triploid, which is one possible reason for the reduced lignin content in triploid E. urophylla. This study provides important insights into transcriptional regulation of lignin biosynthesis in Eucalyptus , and also contributes to revealing the genetic mechanism of lignin content variation in polyploid plants, which are of great significance for promoting the improvement of wood quality in forest trees and polyploid breeding. • EuMYB308 has an important influence on the regulation of lignin content in Eucalyptus urophylla. • A mode of negative regulation of lignin content by EuMYB308 targeting EuLAC17 was identified. • Differential expression of EuMYB308 may be an important reason for the reduced lignin content in triploid Eucalyptus. [ABSTRACT FROM AUTHOR]

Wood properties for dissolving pulp production are little explored in wood quality research, mainly when it comes to eucalyptus trees. Therefore, the objective of the present study is to assess age and genotype impact on the quality of wood from young eucalyptus clones aimed at dissolving pulp production. Five trees from two clones, Eucalyptus urophylla (A) and E. urophylla x E. spp. (B), at the ages of 3 and 5 years, from crops located in Itanagra and Alagoinhas, Bahia State, Brazil, were assessed. Three wooden discs were removed from six trees at positions 0 %, 25 %, 50 %, 75 % and 100 % diameter at breast height (DBH) of the commercial height set for macroscopic characterization and wood chemical, physical and anatomical properties. Material age had impact on heartwood and bark production; and extractives, ash, xylans, galactans, arabinans rates, as well as wood vessels' diameter and frequency. Genotypes had impact on extractives, lignin ash, hemicelluloses, xylans and galactans levels. Thus, wood chemical composition was the property most influenced by factors 'age' and 'genotype'. Furthermore, clone A, at the age of 5 years, was the one with the greatest potential to dissolving pulp production, based on the following findings: the highest basic density (450 kg.m³), the highest glucans rate (48 %) and the lowest hemicellulose concentration (23 %). [Display omitted] • Age and genotype played important role in eucalyptus wood properties. • Wood chemical composition was the property most influenced by factors 'age' and 'genotype. • Eucalyptus urophylla (Clone A), at the age of 5 years, was the one with the greatest potential to dissolving pulp production. • Provided valuable information to optimize future dissolving pulp sustainable production strategies. [ABSTRACT FROM AUTHOR]

Utilizing relatively mild hydrothermal conversion technique (under optimized conditions, 200 °C, 4 h, 1:10 solid-liquid ratio, 0.5 M NaOH), lignocellulosic biomass can be efficiently transformed into humic acids, thereby significantly enhancing its utilization. Additionally, this approach provides a means for precise manipulation of the composition and properties of the resulting humic acids. In this comprehensive study, lignocellulosic biomass, comprising various attributes like coniferous, broadleaf, and grassy species, as well as model components like cellulose, hemicellulose, and lignin, underwent hydrothermal reactions to produce humic acids. Firstly, a systematic evaluation was conducted to determine the influence of operational parameters on the formation of humic acids. Subsequently, the characteristics of humic acids derived from diverse lignocellulosic biomass sources were analyzed and benchmarked against commercial humic acids. Based on the empirical findings, a mechanistic pathway for the generation of humic acids was figured out. The results indicate that the primary stages in the hydrothermal conversion of lignocellulosic biomass to humic acids involve initial hydrolysis into smaller molecular components, followed by further reactions leading to the formation of humic acids. Notably, the interplay between cellulose, hemicellulose, lignin, and other minor components, such as tannins and pectins, plays a pivotal role in the synthesis of humic acids. The characterization of the derived humic acids revealed several noteworthy distinctions from commercial products. In the infrared spectroscopy (FTIR) and elemental analysis (EA) characterization, the synthetic humic acid has more oxygen functional groups, alkane groups and aromatic structures. In the X-ray photoelectron spectroscopy (XPS), the synthetic humic acid has more diverse forms and proportions of elements. In thermogravimetric analysis (TGA), the synthesized humic acid has higher thermal stability. The synthetic humic acid has a rougher surface microstructure. The synthetic humic acid has higher fluorescence intensity in three-dimensional fluorescence spectrum (3D EEM). Lignocellulose biomass raw materials with high wood quality content can obtain higher humic acid yield, but the interaction of cellulose, hemicellulose, lignin and other group components (such as tannins, pectin, etc.) in the hydrothermal process plays an important role in the generation of humic acid. This research offers valuable insights into the chemically driven production of humic acids and the strategic control of their properties, based on the structural and compositional nuances of the raw materials. • Time, temps, & solid-liquid ratio hinder humic acid, latter affects reaction activity. • Cellulose, hemicellulose, & lignin hydrolyze reacting to form humic acid in hydrothermal reactions. • Hydrothermal lignocellulose-derived humic acid has more O-groups, richer composition, & better thermal stability than commercial. • Lignocellulose-derived humic acid has coarser surface microstructure. [ABSTRACT FROM AUTHOR]

Pellet consumption and the number of pellet-fired boilers have been growing steadily in Europe, which is a consequence of their compactness, the automated fuel feeding process and the overall system operation. This increase in the share of biomass-fired boilers is also noticeable in Poland, with automatic wood pellet boilers accounting for the majority of them. However, wood biomass is diverse with respect to its properties, determined by its systematic genus, among other things. Therefore, this research examines a diversity of seven types of pellets produced from various genera of trees sawdust (coniferous and deciduous). This is important as uncertainty about the impact of the raw material properties on the pellet quality and meeting or not market standards are obstacles faced by the sectors using this biofuel. The thermophysical properties and elementary composition were determined, and all results were referred to ISO 17225–2:2021-10 standards, the Pellet Fuels Institute and the Korea Forest Research Institute. The systematic tree genus was found to significantly differentiate all pellet quality parameters, and only pellets made from two out of the seven tree species (P. sylvestris and P. strobus) met the most strict standards contained in each of the three norms. [ABSTRACT FROM AUTHOR]

Eucalypts are the most planted hardwood trees worldwide because of their very rapid growth, exceptional wood quality and adaptability. However, most commercial species and derived hybrids are sensitive to frost, which remains as the largest obstacle to their introduction in warm/temperate climates. As evergreen species, Eucalypts have developed the ability to tolerate frost events based on physiological and molecular responses triggered by previous exposure to cold temperatures, globally named cold acclimation. To characterize the acclimation process in two species with different tolerance to frost, E. grandis (Eg) and E. benthamii (Eb), seedlings were exposed for different times to low temperatures. Frost tolerance was estimated in leaves by an electrolyte leakage assay, and metabolome and morpho-physiological changes studied and correlated to the observed acclimation responses. Eb showed higher basal frost tolerance and an earlier and stronger acclimation response to cold temperatures than in the frost sensitive Eg. Eb was able to modify several morpho-physiological parameters, with a restriction in plant height, leaf area and leaf fresh weight during acclimation. Metabolome characterization allowed us to differentiate species and strengthen our understanding of their acclimation response dynamics. Interestingly, Eb displayed an early phase of sugar accumulation followed by a rise of different metabolites with possible roles as osmolytes and antioxidants, that correlated to frost tolerance and may explain Eb higher capacity to acclimate. This novel approach has helped us to point to the main metabolic processes underlying the cold tolerance acquisition process in two relevant Eucalyptus species. • Eb has higher basal frost tolerance. • Eb and Eg alter its physiology and biochemistry in response to cold temperatures. • Eb acclimates to cold earlier and to a higher extent than Eg. • Metabolome differ between species and are differently affected by cold treatments. • Cold acclimation in Eb triggers different protection mechanisms to withstand frost. [ABSTRACT FROM AUTHOR]

Sape is a popular traditional musical instrument from Sarawak, Malaysia. This instrument is handmade and differs in wood, dimension, design, etc. This impedes the preservation and promotion of the Sape tradition, as well as the development of new Sape instruments. Wood is the primary factor affecting Sape sound, and this study aimed to evaluate the quality of three commonly used types of wood in the instrument manufacturing. Rectangular wood samples were fashioned and tested for physical, vibroacoustic, and timbre characteristics using a flexural vibration test. The objective was to identify the top features influencing the sound quality and develop a reliable method for classifying wood quality. Results showed that Adau wood had the highest quality, followed by Merbau and Tapang wood. Four key features, including acoustic radiation damping coefficient, spectral flux, spectral centroid, and inharmonicity, were selected by the MRMR algorithm and used to train and test various classifiers in MATLAB. The decision tree classifier achieved 98.1% accuracy in predicting wood quality. This study demonstrates the potential of using machine learning to classify Sape wood quality and provides a useful guide for its production. The findings could contribute to the preservation and advancement of this cultural tradition. [ABSTRACT FROM AUTHOR]

Loblolly pine (Pinus taeda) and Slash pine (Pinus elliottii) are important economically and ecologically tree species worldwide. To implement genomic based breeding strategy, genotyping large number of samples is needed. However, huge and complex pines genome make it difficult to obtain abundant and cost-effectively markers. In this study, we designed a SNP array containing 51 K liquid-phased probes based on the published SNPs and probes of the two species, novel Slash pine-specific long-read transcript, and SNPs obtained from a double digest Restriction-Site Associated DNA sequencing (ddRADseq). We performed targeted capture sequencing using the developed SNP array on three pine species of Loblolly, Slash, and Caribbean pine (Pinus caribaea). The probe capture had an efficiency of 68.26% on average. Principal Component Analysis (PCA), phylogenetic analysis, and genetic structure analysis of 28,670 SNPs genotyped for the three pine species demonstrated the transferability of the SNP array for the three pines. Furthermore, we genotyped 221 range-wide Slash pine genotypes, analyzed their genetic diversity and performed a genome-wide association study (GWAS). We identified 95 SNPs significantly associated with growth and wood quality traits of Slash pine. We have identified potential roles of the MYB2 and MYB46 transcription factors in regulating cell cycle and differentiation in Slash pine, while also suggesting that AP2/ERF and Glycosyl hydrolase may play significant roles in wood formation processes. This new SNP array can be widely applied in future molecular breeding research of conifers. ● Innovative Genotyping Tool: Developed a novel and efficient 51k liquid-phased probe for Loblolly and Slash pine genotyping in breeding. ● Species Applicability: Demonstrated the versatility of the 51k probes, offering a valuable tool for broader pine genotyping applications. ● Breeding Program Success: Successfully applied the SNP array to breeding programs of Slash, Loblolly, and Caribbean pine. ● GWAS Insights: Unveiled genetic insights into growth and wood traits in Slash pine, laying the foundation for precisionbreeding. [ABSTRACT FROM AUTHOR]

Woody biomass pellets' demand for primary energy production is increasing. To guarantee sustainable and cost-efficient pellet production the diversification of biomass feedstock is mandatory. In this work it is proposed to re-use the solid biochar obtained from pyrolysis of eucalyptus (PEc) at 700 °C as an additive to produce enhanced pine sawdust (PIN) pellets. The process required the addition of glycerol as a lubricant in a percentage of 1 and 2 wt% per 5 and 10 wt% of pyrolyzed eucalyptus in the blend, respectively. Small additions of PEc enhanced PIN pellets' grindability and water-resistance, providing products with remarkable values of durability (up to 99%), net calorific value (up to 20 MJ/kg), energy density (up to 13.3 GJ/m3), and particle density (up to 1.24 g/cm3). N, S, chlorine, and heavy metals contents were also analyzed. The proposed pellets fulfill the A1/A2 and the I1/I2 quality classes for domestic and industrial wood pellets, respectively. A preliminary economic evaluation indicated that pellets made up from a mixture of 90% PIN and 10% PEc are competitive compared to raw PIN pellets, with expected savings in the costs of production, energy, transport, and construction of a storage site of 4, 13, 10 and 7%, respectively. • Valorization of a solid waste, eucalyptus biochar (PEc), is proposed. • Pine sawdust (PIN) pellets with PEc and glycerol as additives are formulated. • PEc addition below 10 wt% enhances PIN pellets' heating value and energy density. • PEc addition below 10 wt% enhances PIN pellets' grindability and water-resistance. • PEc-PIN pellets are economically competitive when compared to PIN. [ABSTRACT FROM AUTHOR]

Considering the focus of the current European policy in promoting the reuse of waste products and increasing the share of renewable energies, waste wood is becoming an appealing resource rather than a product to dispose of. End-life waste wood products could be used for the production of panel board or as feedstock in combustion units. In this study, waste wood samples have been collected in a big panel board company, and have been analyzed by means of Near Infrared Spectroscopy. Principal Component Analysis has been used in order to investigate the variability of the material, and Partial-Least Squares regression models have been developed for the prediction of moisture content and net calorific value. The results indicate that both models could be used in quality control applications, and Near Infrared Spectroscopy can be considered as a tool for the rapid evaluation of waste wood parameters for energy applications. Considering the high correlation between the two parameters it is also possible to analyze only the moisture content and have indications about the net calorific value using a simple linear regression, with positive effects in terms of quality control and the reuse of the waste wood material. • Waste wood variability and composition are investigated. • PCA indicates on how to take into account the sampling procedure. • NIR spectroscopy can be used for the rapid evaluation of the main energy parameters. • A linear regression towards moisture gives indications about net calorific value. • The real-time quality control of the product is possible using NIR spectroscopy. [ABSTRACT FROM AUTHOR]

• Ultrasonic welding is a fast joining of thermoplastic dowel-wood board assembly. • Density of wood board plays an important role in ultrasonic welding. • Dowel pulling force inversely proportional to the depth of the drilled hole. • Ultrasonic thermoplastic dowel welding is not suitable for wet wood boards. [Display omitted] This study reports on an ultrasonic welding application for the assembly of a thermoplastic dowel and a wood board. Three types of medium density particleboards (MDP) and fiberboards (MDF) were used to indicate applicability of ultrasonic welding to fix a plastic wedge dowel into the wood boards: light-weight, standard, and heavy. Plastic wedge dowels made of resin nylon thermoplastic polyamide PA66 were used to compose ultrasonically welded wood boards' joints. Ultrasonic welding is a joining technique without any additional substances, such as adhesives or solvents. It possesses local heating of only the joint area, short cycle times in the range of just a few seconds, and comparatively low cost-efficiency. During the ultrasonic consolidation process, energy generated from an ultrasonic transducer is transferred to the joint components (dowel – wood board) in the form of ultrasonic oscillation. The quality of the welded joint is mainly influenced by the density of the wood board, the quality of wood particles bonding, the depth and diameter of the drilled hole. The size of the contact area of the drilled hole (hole geometry, density and the size of hole walls) is also very important because the molten thermoplastic requires enough space to penetrate and settle to form a solid assembly. [ABSTRACT FROM AUTHOR]

Forest yield is significantly influenced by silvicultural practices. Moreover, environmental conditions play key role in trees' growth and wood features. Accordingly, the aim of the current study is to explore the effects of age, location, fertilization and thinning on the wood quality of Pinus taeda trees grown in different sites in Southern Brazil. Trees collected in seven municipalities in Southern Brazil were used to assess age impact on wood quality. Trees collected in three municipalities (Jaguariaíva and Ponta Grossa in Paraná State, and Rio Negrinho in Santa Catarina State) were assessed to analyze forestry practices. Collected trees were subjected to four different treatments: PS (No thinning and no fertilization), PF (No thinning and fertilization), US (Thinning and no fertilization), and UF (Thinning and fertilization). Age had significant impact on Pinus taeda wood's basic density; younger trees presented lower density. In addition, the adopted forestry methods did not affect this species' basic wood density. Non-fertilized trees presented higher density than the fertilized ones. Trees grown in different locations in Jaguariaíva County recorded the highest wood density. Water shortage was identified as the main climatic factor influencing wood density. • Fertilization or thinning do not significantly affect the density of Pinus taeda wood. • Regions with increased water deficits tended to have higher densities. • The correlation between frost and growth suggests possible resilience of Pinus taeda. [ABSTRACT FROM AUTHOR]

Pilot-scale oil heat treatment was conducted to enhance the quality of poplar wood obtained from a fast-growing plantation. Three target temperatures, namely 180, 190, and 200 ˚C, were chosen for the oil heat treatment process. Clear, small specimens were cut from the lumber, following the prescribed standards for assessing wood quality. Light microscopy revealed the ruptures and deformation of the wood cell wall as the treatment temperature increased. The volumetric swelling of the treated specimen decreased proportionally with the increase in treatment temperature. The impact of oil heat treatment on the mechanical properties of wood varied depending on the specific type of mechanical strength and processing temperature. The modulus of rupture, toughness, and hardness of the treated specimens drastically decreased at 200°C. However, the specimens treated at 200°C exhibited much lower mass loss during the fungal decay test. The results of the analytical test showed an increase in the crystalline cellulose content and thermal stability of the treated wood, due to the thermal degradation of hemicelluloses and amorphous regions of cellulose. Overall, it is concluded that oil heat treatment of poplar wood in the optimal temperature is an efficient approach to upgrade its quality with minimal reduction in mechanical strength. [Display omitted] • The potential of a pilot - scale oil heat treatment (OHT) was evaluated to upgrade the quality of poplar wood. • Higher treatment temperature resulted in higher durability and hydrophobicity. • Mechanical properties differed depending on the heating temperature. • Hemicellulose degradation was identified as a key factor driving changes in wood characteristics during soybean oil heat treatment. [ABSTRACT FROM AUTHOR]

Contamination of wood chip fuels with soil material, e. g. during logging operations, might result in a deterioration of fuel quality and in elevated gaseous and particulate emissions, corrosion, or slag formation during combustion in biomass boilers. In contrast, fuel upgrading by washing/screening might improve combustion behaviour. To investigate these effects, wood chips from stemwood and forest residues originating from three different forest growing regions (A to C) in Bavaria, Germany, were deliberately contaminated with mineral soils at two mixing ratios (5 %, 10 %) or were mechanically upgraded by screening or washing (only fuels from region A). Contamination was performed using three typical forest soils from Bavaria that corresponded to the selected fuel growing areas (soil A, B and C). Wood chips were tested for fuel quality according to ISO standards for solid biofuels and combusted in a 30 kW biomass boiler. Throughout the trials, fuel upgrading usually improved combustion behaviour. Total particulate matter (TPM) emissions increased for wood chips from stemwood when contaminated with soil A and C from 50 mg/m3 up to 236 mg/m3 (STC), compared to the reference fuel, while emissions for wood chips contaminated with soil B remained constant at approx. 50 mg/m3 (STC). Carbon monoxide (CO) emissions decreased for contaminated wood chips by up to 89 %. For NO X emissions, no clear effect was observed. In addition, contamination mostly increased slagging of fuels when contaminated with soil. Overall, the contamination of woody biomass had a noticeable effect on pollutant emissions and slag formation and should be avoided. • Wood chips were contaminated with mineral soil or upgraded by screening/washing. • Fuels were analyzed for physical/chemical fuel quality and combusted in a 30 kw boiler. • In contrast to contamination, fuel upgrading usually improved combustion behaviour. • TPM emissions increased for wood contaminated with soil A and C but not for soil B. • Slagging of fuels occurred when wood chips were contaminated with soil material. [ABSTRACT FROM AUTHOR]

Charcoal productivity in brick kilns is controlled by factors such as, the pyrolysis process and kind of raw material, which impose a challenge for the selection of the best clones. This study investigates the tree growth characteristics as a parameter for the improvement of selection and classification of Eucalyptus clones, with the quality and availability required by the steel industry, in addition to the properties of wood and charcoal. Parameters as the diameter at breast height (DBH), total height, and wood basic density (WBD) of fourteen clones were measured. Wood specimens were converted to charcoal in laboratory conditions and the carbonization yields, charcoal properties, and the volume of wood required to produce 1 t of charcoal (specific consumption) were evaluated. Eucalyptus clones with DBH ≥15.1 cm, WBD ≥560 kg/m3, and gravimetric yield ≥35% provided low specific consumption (<5.1 m³/t), increased brick kilns productivity, and resulted in denser charcoals (380 kg/m3). Clones with WBD ≤500 kg/m3 are not recommended for steel charcoal production. The E. urophylla x E. camaldulensis hybrid (clone 1004), E. urophylla (clone 1009), and E. grandis hybrid (clone 1039) highlighted due to the productivity, bioreducer quality, and specific consumption (<5.2 m³/t). Image 1 • Eucalyptus with wood density ≤500 kg/m3 is not recommended for energy purposes. • The diameter at breast height is criterion for classification of Eucalyptus clones. • Wood density is a key criterion for selecting charcoal for steel production. • Wood density, tree growth, and pyrolysis yields indicates best clones. • The carbonization of wood with WBD ≥560 kg/m3 results in denser charcoals. [ABSTRACT FROM AUTHOR]

Cryptomeria fortunei is the indigenous evergreen coniferous timber species in southern China, valued for its superior wood quality, which frequently finds industrial applications. MiRNAs (microRNAs) can be involved in regulating various aspects of plant growth, and more and more studies have explored miRNAs related to growth and development, but among them, the ones on C. fortunei are relatively rare. In this study, we screened miRNAs that were differentially expressed during vascular cambium development, and chose miR159a and CfMYB37 as candidate genes for cloning and functional validation. The results showed that miR159a had CfMYB37 as a target gene and that there was a distinct negative regulatory relationship between miR159a and CfMYB37 in C. fortunei. 35 S::miR159a plants were taller than WT and had thicker stems than WT, and miR159a encouraged the growth of xylem cells and lignin. While 35 S::mCfMYB37 plants had the opposite phenotype to 35 S::miR159a plants, with considerably lower lignin content and xylem cell layer number compared to WT, 35 S::CfMYB37 plants lacked a distinctive phenotype. This suggests that the miR159- CfMYB37 module can control plant growth and xylem development. For the following investigation of C. fortunei 's growth and vascular cambium development as well as the enhancement of its wood qualities, this work serves as a crucial theoretical foundation. • Screening from transcriptome and miRNA sequencing data for differentially expressed miR159 and CfMYB37 in C. fortunei. • MiR159a and its target gene CfMYB37 were cloned from C. fortunei. • MiR159 negatively regulates the expression of CfMYB37 in different growth stages of C. fortunei. • CfMYB37 was nucleus localization proteins. • The miR159a-CfMYB37 module plays an important role in the development of xylem and regulates the synthesis of lignin. [ABSTRACT FROM AUTHOR]

Trees play a pivotal role in terrestrial ecosystems as well as being an important natural resource. These attributes are primarily associated with the capacity of trees to continuously produce woody tissue from the vascular cambium, a ring of stem cells located just beneath the bark. Long-lived trees are exposed to a myriad of biological and environmental stresses that may result in wounding, leading to a loss of bark and the underlying vascular cambium. This affects both wood formation and the quality of timber arising from the tree. In addition, the exposed wound site is a potential entry point for pathogens that cause disease. In response to wounding, trees have the capacity to regenerate lost or damaged tissues at this site. Investigating gene expression changes associated with different stages of wound healing reveals complex and dynamic changes in the activity of transcription factors, signalling pathways and hormone responses. In this review we summarise these data and discuss how they relate to our current understanding of vascular cambium formation and xylem differentiation during secondary growth. Based on this analysis, a model for wound healing that provides the conceptual foundations for future studies aimed at understanding this intriguing process is proposed. • A review summarising current knowledge of wound response and proposing an updated gene regulatory network for regeneration of secondary vascular tissues in wounded trees. • Discuss limitations and future improvement to methodologies used to investigate transcriptional responses to wounding in trees. [ABSTRACT FROM AUTHOR]

Heartwood are mainly used as Castanopsis hystrix valuable wood, which play a vital role in determining the quality of wood for sales, value assessment, and consumption. There are two defects in the heartwood produced by C. hystrix commercial forests: a low proportion of heartwood, reducing the output of high-value wood, and the uneven color of the heartwood from red to reddish-brown, affecting its visual appearance and decorative performance. As these two defects seriously influence the quality of C. hystrix heartwood, breeding of high-yield and high-quality heartwood varieties is critical. The present study examined 20-year-old C. hystrix forests in Yulin, Liuzhou, and Pingxiang counties in China. Through analysis of the proportion, density, brightness L * , chroma a * , and chroma b* of heartwood, genetic variation in each trait was described, genetic parameters were estimated, and the genotype by environment interaction effect was clarified. The average value of the above traits were 34.76%, 0.67 g/cm3, 52.22, 13.90, and 17.25, respectively. The results of the joint three-site variance analysis reveal that heartwood proportion, density, chroma a * , chroma b * have significant (p < 0.05) or extremely significant (p < 0.01) genotype, environment, and their interaction effects, with family heritability values of 0.25, 0.23, 0.31, and 0.54, respectively. Based on the BLUP–GGE biplot of single and multiple traits, the families with strong adaptability and stable genetics were selected. The average genetic gains in heartwood proportion, density, chroma a * , and chroma b* from families 7, 8 and 9 were 5.83%, 0.02%, 1.04%, and 3.37%, respectively. The three families selected in this study were vital for promotion and utilization, providing a theoretical foundation for the innovation of C. hystrix germplasm and precise improvement of wood quality in South China. • This study examined Castanopsis hystrix forests in three provinces in China. • P , D , L * , a * , and b* of C. hystrix heartwood were analyzed. • Block and family were the critical sources of variation in P , D , L * , a * , and b*. • Our results provide a foundation for C. hystrix plantations in South China. [ABSTRACT FROM AUTHOR]

Wood chips are the primary sources of raw materials for numerous industries, including pelleting mills, biorefineries, pulp-and-paper industries, and biomass-based power generation facilities. Unfortunately, when wood chips are utilized as a renewable and environmentally friendly resource, industries are constantly challenged by the consistency of the wood chip qualities (e.g., moisture/ash contents, size distributions) - a historically recognized problem on a global scale. Among other wood chip quality attributes, the moisture content is considered the most pressing one as it directly impacts the energy content, storage stability, and handling properties of the raw and finished products. Therefore, accurate wood chip moisture content prediction can help optimize the drying process and reduce energy consumption. In this review, a survey was conducted on various techniques and models employed for predicting wood chip moisture content. The advantages and limitations of these approaches, as well as their potential applications and future directions were also discussed. This review aims to provide a comprehensive overview of the current state-of-the-art in wood chip moisture content prediction and to highlight the challenges and opportunities for further research and development in this field. • Oven drying is the most used method despite being slow and prone to sampling errors. • Indirect methods are fast but have individual shortcomings based on applications. • Due to reliance on direct method for data labeling, wood chip datasets are small. • Box-based data collection methods and regression-based models are prevalent. [ABSTRACT FROM AUTHOR]

Wood modification using polyesterification of sorbitol and citric acid is a novel environmentally friendly strategy for wood protection improving its dimensional stability and acts against fungal deterioration. Inelastic Raman scattering is sensitive to the molecules of high polarizability and both lignocellulose and aliphatic esters formed during the treatment are polar. Therefore, in the present study, the quality control of the treatment using a handheld Raman spectrometer equipped with 830 nm laser is suggested as a rapid and reliable approach. Raman spectra from six wood modification levels (resulting in different weight percent gain, WPG) of three different wood species (Silver birch, Scots pine and Norway spruce) as well as three sample preparation strategies (intact, sanded and milled wood samples) were collected, and further analyzed using a chemometric method. Best performing models based on Powered Partial Least Squares Regression predicted the WPG level at R2 = 0.85, 0.95 and 0.98 for birch, pine and spruce, respectively. In addition, a clear separation between hard and soft wood species was also captured. Especially for softwood species, the sample preparation method affected the model accuracy, revealing the best performance in milled material. It is concluded that by using handheld Raman spectrometer it is possible to perform accurate quality control of wood modified by polyesterification of citric acid and sorbitol. [Display omitted] • A quick and accurate quality control is required for broad application of wood protection using sorbitol and citric acid. • Handheld Raman spectrometer is a promising tool for quality control of wood treated with citric acid and sorbitol. • Chemometric modeling allows to predict the weight percent gain (WPG) level with high accuracy for birch, pine, and spruce. • The sample preparation method affected the model accuracy, with milled material performing the best for softwood species. [ABSTRACT FROM AUTHOR]

Outdoor pollutants are well documented and monitored due to existing air quality regulations in many parts of the world. However, as information regarding indoor air quality is still limited, there are not enough information for indoor air pollutants. Indoor air quality pollutants are harmful to human health and are especially dangerous to vulnerable populations, such as elderly people and children. The effects of indoor environment and indoor air pollutants on children and the elderly are being studied worldwide. Ultimately, this paper highlights the prospect of remodeling wood interior, an indoor air pollutants reduction strategy that will help improve indoor air quality and public health. Wood is an environmentally friendly building material with low thermal conductivity and humidity control, and wood interior remodeling can protect people's health from indoor air pollutants. In this paper, twelve indoor air quality factors were measured: comfort factor (temperature and relative humidity), particulate matter, biological pollutants (total airborne bacteria), Airborne asbestos fibers, and chemical pollutants (carbon monoxide and dioxide, formaldehyde, volatile organic compounds, radon, ozone and nitrogen oxides). The average value of the indoor air quality factors for 12 welfare facilities is as follows. The average particulate matter was less than 12μg/㎥, the average of carbon dioxidewas 754.2 ppm, the formaldehyde was 46.6μg/㎥, the volatile organic compounds was 335.0μg/㎥, the total airborne bacteria was 37.8 CFU/㎥and the radon was 59.5Bq/㎥. As a result, almost all of the measurement locations were found to satisfy the international indoor air quality guidelines. It is thus judged that interior remodeling using wood can improve the indoor air quality of welfare facilities, and that it is necessary to constantly measure indoor air quality for accurate indoor air quality analysis. • Twelve welfare facilities were remodeled using wood materials. • Twelve indoor air quality factors include biological pollutants were measured. • The PM value can be lowered when the room interior is remodeled with wood. • The higher the quantity of wood used, the lower the concentration of HCHO. • This paper established a basis for the improvement of IAQ with wood remodeling. [ABSTRACT FROM AUTHOR]

• First genomic selection study in forest trees that compare GBLUP and ssGBLUP approaches. • ssGBLUP takes into account genotyped and non-genotyped trees simultaneously in the same evaluation. • ssGBLUP provided higher prediction accuracy and lower bias of breeding values than GBLUP. • ssGBLUP is more relevant for low-heritable traits. Genomic Best Linear Unbiased Prediction (GBLUP) in tree breeding typically only uses information from genotyped trees. However, information from phenotyped but non-genotyped trees can also be highly valuable. The single-step GBLUP approach (ssGBLUP) allows genomic prediction to take into account both genotyped and non-genotyped trees simultaneously in a single evaluation. In this study, we investigated the advantage, in terms of breeding value accuracy and bias, of including phenotypic observation from non-genotyped trees in a standard tree GBLUP evaluation. We compared the efficiency of the conventional pedigree-based (ABLUP), GBLUP and ssGBLUP approaches to evaluate eight growth and wood quality traits in a Eucalyptus hybrid population, genotyped with 33,398 single nucleotide polymorphisms (SNPs) using the EucHIP60k. Theoretical accuracies, predictive ability and bias were calculated by ten-fold cross validation on all traits. The use of additional phenotypic information from non-genotyped trees by means of ssGBLUP provided higher predictive ability (from 37% to 75%) and lower prediction bias (from 21% to 73%) for the genetic component of non-phenotyped but genotyped trees when compared to GBLUP. The increase (decrease) in the prediction accuracy (bias) became stronger as trait heritability decreased. We concluded that ssGBLUP is a promising breeding tool to improve accuracies and bias over classical GBLUP for genomic evaluation in Eucalyptus breeding practice. [ABSTRACT FROM AUTHOR]

Highlights • A simple and easy-to-use gamma-ray densitometer for application in wood industry is designed. • The designed densitometer works based on calibration of the output signal of the detector. • Improvement of the apparatus is made by optimization of the temporal and geometrical designing parameters. • The designed densitometer can also be used for densitometry of other types of samples, like glasses, plastics and etc. Abstract One of the most important indicators of wood quality is its density. Structural and physical properties of wood products, for instance their strength, are strongly related to the density of wood. Nuclear densitometry is one of the most accurate methods for measuring density that is based on attenuation detection of gamma ray flux with a certain activity. There are three main methods for density measurement by gamma rays: transmission, backscatter and reactive methods. In this paper, based on the transmission method, two experimental set-ups were prepared for measuring the density of 10 different kinds of wood within the density range of 0.317–0.819 g/cm3. By optimizing the counting time and source-to-detector distance, density of woods were measured with the accuracy of 0.01 g/cm3. Compared with the commonly used methods that are time-consuming and expensive, the proposed method is simple, rapid, precise, non-destructive, and more reliable. [ABSTRACT FROM AUTHOR]

Highlights • Wood quality prediction models for 8 attributes that govern end-product potential. • Confirmatory support for the application of hierarchical mixed-effects models. • Size-dependent attribute developmental patterns enabled model integration. • Enhanced structural stand density management models for value-based management. • Species-specific variation in end-product potential with management intensification. Abstract The objectives of this study were to (1) develop wood quality prediction models for a suite of commercially-relevant jack pine (Pinus banksiana Lamb.) fibre attributes (wood density (W d), microfibril angle (M a), modulus of elasticity (M e), fibre coarseness (C o), tracheid wall thickness (W t), tracheid radial (D r) and tangential (D t) diameters and specific surface area (S a)), (2) given (1), incorporate the parameterized equations within structural stand density management models (SSDMMs), and (3) given (2), exemplify their utility in silvicultural decision-making via the comparative assessment of attribute outcomes arising from operationally-relevant crop plans. Analytically, the equations were developed deploying Silviscan-determined attributes derived from transverse breast-height radial xylem sequences obtained from 61 trees sampled from 2 geographically-separated thinning experiments located in the central region of the Canadian Boreal Forest Region. Hierarchical mixed-effects regression modeling combined with cross-validation procedures were used to specify, parameterize and evaluate the attribute-specific prediction equations. Overall, the results revealed that the attribute trajectories were size-dependent and the resultant models were adequate in terms of their goodness-of-fit characteristics (e.g., I2 values of 75, 71, 71, 66, 60, 55, 49 and 38% for C o , M e , W t , S a , W d , M a , D r and D t respectively), lack-of-fit indicators (e.g., temporally invariant patterns of absolute and relative errors devoid of evidence of systematic bias), and predictive performance (e.g., 95% probability that 95% of all future relative D t , D r , S a , W d , C o , W t , M e and M a errors would be within ±5, ±9, ±11, ±12, ±12, ±13, ±35 and ±43% of their true values, respectively). Incorporating the jack pine equations along with a similar suite of functions previously developed for black spruce (Picea mariana (Mill) B.S.P) into the SSDMM analytical framework, yielded a pair of enhanced stand-type-specific (natural-origin and planted stands) decision-support systems for each species. These systems enabled the estimation of attribute-specific developmental trajectories for the rotational tree population from which diameter-class and stand-level wood quality performance measures were derived. As exemplified, the development of size-dependent fibre attribute prediction models and their subsequent integration within SSDMMs provides forest managers with a decision-support platform for evaluating and comparing end-product-related consequences of selected crop plans. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Properties of maritime pine resin dried at different temperatures have been studied. • Two drying temperatures were tested and the results were measured via TMA and TGA. • Samples dried at a 60 °C have a high softening point after 3 months at room temperature. • For samples dried at a 90 °C, rosin and turpentine can associate to form a gel. • Original results in view of preventing exudation on outdoor wooden boards. Abstract The interactions between rosin and turpentine during the drying process were studied to better understand wood pine resin exudation in outdoor use under solar heat. Resin exudation is an important concern for industrials, as it may strongly decrease the wood's aesthetic value. Resin viscosity change with temperature variations induced an alteration in the resin's appearance from 65 °C. Resin, which is opaque at ambient temperature, becomes translucent above 65 °C. Resin samples were dried at temperatures respectively lower and higher (60 °C and 90 °C for 16 h) than the threshold. For all measurements, eight resins from different trees were harvested using an isolation technique developed by Biogemme®. After drying, samples were kept at room temperature, and the softening point temperature and the remaining turpentine amount were measured over time using Thermomechanical Analysis (TMA) and Thermogravimetric Analysis (TGA) respectively. After three months, the results show that a majority of samples dried at 90 °C have a softening temperature under 25 °C, while all the samples dried at 60 °C have a softening temperature above 60 °C. These results can be explained by a modification of the physical properties of the samples dried at 90 °C: they start to behave like gels, preventing the evaporation of their liquid phases. These new results highlight some properties of resin that may be interesting to develop a new strategy for reducing resin exudation on outdoor wood siding, by fixing the resin inside the wood during the industrial drying process. [ABSTRACT FROM AUTHOR]

Highlights • Rings formed during the defoliation had a significant and progressive loss of biomass. • Defoliation significantly reduced latewood density for black spruce and balsam fir. • Average ring density was reduced only in black spruce. • The changes in growth and density were associated with changes in anatomical features. • Significant reductions occurred in cell-wall thickness after 3rd year of defoliation. Abstract Spruce budworm (SBW – Choristoneura fumiferana Clem.) is one of the most damaging defoliating insects in the coniferous forests of eastern North America. In Canada, the widely distributed balsam fir (Abies balsamea L. (Mill)) and black spruce (Picea mariana B.S.P. (Mill)) are its most important hosts. Defoliation by SBW reduces growth in the host trees and can lead to host mortality. Although SBW impacts on growth are well documented, much less is known about changes in wood properties resulting from defoliation. To address this knowledge gap, we sampled 36 SBW-infested stands located in the boreal forest of Quebec (Canada) to determine whether defoliation modifies the wood quality of affected trees. The selected stands had been subjected to one to four years of SBW defoliation. For both species, we assessed ring growth, wood density, and the anatomical characteristics of stem wood formed during the outbreak years. We determined that rings formed during the SBW outbreak had a significant and progressive loss of biomass production with a longer duration of defoliation. SBW significantly reduced latewood density in the second and third year of defoliation for black spruce and the third and fourth year for balsam fir. Average ring density was reduced only in black spruce and only after four years of defoliation. The observed changes in growth and density were associated with changes in anatomical features. While the cellular characteristics of the earlywood remained fairly constant, significant reductions occurred in latewood cell-wall thickness after three years of defoliation. Our study shows that not only do SBW outbreaks reduce annual radial growth, but the cellular characteristics in latewood cells are also modified momentarily. Thus, SBW outbreaks affect wood density and quality in both black spruce and balsam fir. [ABSTRACT FROM AUTHOR]

• Wood waste was characterised according to application, type and quality grade. • Physical impurities accounts for 13–59% of wood waste. • Behaviour of inorganic elements varies with wood waste characteristics. • Low-quality wood waste shows higher metal concentrations. • Level of phenols, PAHs and PCBs is below 10 mg/kg dw. Recycling of post-consumer wood waste into particleboard may be hindered by the presence of physical and chemical impurities in the waste stream, therefore calling for increased attention on the quality of wood waste. However, wood waste comprises several uses/types of wood, along with different levels of contamination. This study provides the detailed sampling and characterisation of wood waste according to its source, type and resource quality grade. Eight tonnes of wood waste, intended for recycling and collected at three Danish recycling centres, were subdivided into 34 individual material fractions and characterised with respect to the presence of three classes of physical impurities (misplacements, interfering materials and low-quality wood waste) as well as chemical concentrations of more than hundred chemical elements and persistent organic pollutants (POPs). The results demonstrated that contaminant and concentration levels vary significantly according to wood waste type and source, thus emphasising that wood waste should not be viewed as a single material flow but rather be understood and managed according to the presence of individual fractions. Including only clean wood waste fractions at the three recycling centres, 41–87% of the collected wood waste per weight could be recycled – the rest being physical impurities. The results showed that chemical contamination was significantly higher for low-quality wood waste, thus clearly indicating that improvements in separate collection, sorting and handling of wood waste may improve the resource quality of wood waste and potentially achieve cleaner recycling practices. [ABSTRACT FROM AUTHOR]

Highlights • Crown social class affects acoustic velocity and mechanical properties of timber. • Tree slenderness also has an effect, the direction varies with crown social class. • The effect of crown projection area on timber quality is likely positive. • Crown ratio, crown eccentricity or crown roundness have no effect on timber quality. • Branchiness is not the main cause of the differences found. Abstract The relationships between several crown and tree properties and timber quality were examined on three softwood species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Norway spruce (Picea abies (L.) H. Karst) and Sitka spruce (Picea sitchensis (Bong.) Carr). Crown and stem characteristics were collected on 487 standing trees, and their acoustic velocity measured using a stress-wave device. Of the trees measured, 60 were chosen for further testing, stratified by crown social class and cut into structural sized boards (N = 1342). Each board was assessed with regard to knots using a grading X-ray machine, after which all boards were destructively tested in four-point bending and their mechanical properties (elastic modulus, bending strength and density) evaluated. To exclude the effect of branchiness across the crown social classes, mechanical properties were also examined on small clear samples cut from the undamaged section of the tested boards, a total of 1303 specimens were tested destructively in bending. Multi-level models based on Bayesian data analysis were used to evaluate the relationships between recorded characteristics, acoustic velocities and mechanical properties. Considerable differences in acoustic velocities were found between crown social classes, with suppressed trees having the highest velocities. This trend was also confirmed in mechanical properties of structural-sized boards and small clear specimens, suggesting that branchiness is not the primary cause of differences. Results indicate that slenderness affects both tree stiffness and the properties of sawn timber differently across the crown social classes. The relationship is negative in suppressed trees (increasing slenderness leads to a decrease in velocity or mechanical properties) and positive in dominant and co-dominant trees. The effect of crown projection area on either tree acoustic velocity or mechanical properties differs between social classes. In general, it was found to be positive, therefore an increase in crown projection area leads to an increase in either tree acoustic velocity or wood properties of timber. This trend is more evident in sawn timber than in acoustic velocities. The effects appear to be species dependant. No evidence was found of the effect of crown ratio, crown eccentricity or crown roundness on either the examined wood properties or acoustic velocities. Results confirm that there is a link between crown/stem development and timber quality. They indicate that in order to increase the overall quality of timber produced, the proportions of crown social classes in final stand composition should be adjusted with thinning. [ABSTRACT FROM AUTHOR]

Highlights • A method for assessing wood density on large increment cores sampling is described. • The method based on X-ray CT scanning is fast (3000 samples/h) and semi-automatic. • The method was found to be accurate and unbiased for 5 mm diameter cores. • The software outputs radial profiles of density. • Correct mean density taking into account radial variations can be computed. • The method is yet applied by the French forest inventory on thousands of cores. Abstract Increment cores are often used in wood science for measuring wood density of trees non destructively and at large scale, for instance with the objective to assess the available biomass in a forest resource. This paper presents a software allowing to measure by X-ray computed tomography (CT) the wood density of thousands increment cores. The software is able to process 3000 cores per hour semi-automatically. Manual intervention may be required to control and eventually adjust the positioning of the cores. The software was tested on 30 trees from 13 temperate species. Two increment cores were taken from each tree: one 5 mm diameter core and one 4 mm diameter core. The obtained CT density of the cores was compared to reference data obtained by volume and mass measurement on the 5 mm cores. The reference data were used for tuning the software settings by leave-one-out cross validation method. The obtained root mean square error was below 10 kg/m3 (1.7%) for the 5 mm cores. For the 4 mm cores, the root mean square difference with the reference density of the 5 mm cores was 25 kg/m3 (4.2%). [ABSTRACT FROM AUTHOR]

Flavonoids are secondary metabolites that serve as essential regulators of the growth, development, and adaptability of plants in response to various environmental stressors. Populus serves as a model system for research focused on woody plants. While a comprehensive understanding of the pathways that govern flavonoid biosynthesis is essential to effectively improve the quality and stress tolerance of wood, at present the factors that regulate this process in Populus have yet to be fully elucidated. Here, a candidate gene association analysis (P = 1.43 × 10−5) was employed to ultimately identify and characterize the flavonoid metabolite-associated YABBY transcription factor (TF) family member PtoYABBY5. At a functional level, PtoYABBY5 was found to interact with the key flavonoid biosynthesis-related TF PtoMYB43, a key TF for flavonoid biosynthesis. Dual-luciferase assays also revealed that the ethylene response regulator PtoERF72 positively regulates PtoYABBY5 expression. Overall, these data highlight PtoYABBY5 as an important and central component of the transcriptional machinery that controls the biosynthesis of flavonoids in Populus. By offering new insight into the regulation of flavonoid production at the transcriptional level, these results may provide new opportunities to improve the stress resistance and quality of wood derived from this economically important species of tree. [Display omitted] • The mechanism by which PtoYABBY5 regulates flavonoid metabolite synthesis in Populus leaves is described. • The PtoYABBY5-PtoMYB43 module was used to study the signaling pathway involved in flavonoid metabolite synthesis. • The roles of flavonoid metabolites in the growth and development of Populus trees and stress tolerance were elucidated. [ABSTRACT FROM AUTHOR]

• We studied 16 sites, 18 clones and stocking 480 to 3300 trees ha−1. • High stocking doubled growth on sites with no water deficit; no effect on driest sites. • Stocking response was higher for more productive genotypes. • Maximum stocking for > 80% survival ranged from 2900 to 900 trees ha−1. • Optimal stocking tests are most important for high-productivity clones and sites. Stocking in forests strongly influence stand growth by influencing resource capture, tree survival, and competition between trees and understory vegetation. Many studies have examined these patterns for specific locations and conditions, though with limited populations of inference. The influence of stocking was examined in the TECHS experimental platform, at 16 sites, with 18 clones, across a 2100 km geographic gradient. Stocking was examined by varying spacing within columns, with constant (3-m) spacing between rows. We examined how wood production and quality related to genotypes and environmental conditions, with stocking ranging from 480 to 3300 trees ha−1. Mean annual increment (Mg ha−1 yr−1) for the entire rotation increased with stocking, asymptoting above 1500 trees ha−1. Water-stressed sites had much lower responses to stocking levels than wetter sites. The three driest sites showed only a 25% increase in MAI (7 to 9 Mg ha−1 yr−1) with stocking increases from 480 to 3300 trees ha−1, whereas the 3 most productive sites increased by 50% (20 Mg ha−1 yr−1 to 30 Mg ha−1 yr−1). A similar result occurred for the clones, where the response to the change in stocking was higher in the more productive clones. From a qualitative point of view, tree breakage declined as stocking increased, going from 0% of broken trees in the highest stocking to a maximum of 3% with the stocking of around 480 trees ha−1. Injury to trees increased with stocking, going from about 4 to 9%. Mortality showed a similar pattern, increasing from 8 to 14% with increasing stocking. The percentage of intact (surviving, undamaged) trees at the lowest stocking was 83%, reaching a peak of 94% between 700 and 1100 trees ha−1, declining again to about 85% at the densest stocking. Survival rates declined when stocking exceeded 2900 trees ha−1 on wetter sites, compared with just 900 trees ha−1 on the driest sites. Overall, an increase in stocking from 480 trees ha−1 to 3300 trees ha−1 led to 50% increase in growth. To put this in perspective, the poorest 25% of sites averaged 59% less growth than the top 25%. The poorest 25% of genotypes grew 47% less than the best 25%. The interactions of effects, such as stocking by site, had effects that were of the same magnitude as these main effects. Management decisions about optimal stocking may be substantially improved by considering the main effects and especially their interactions. [ABSTRACT FROM AUTHOR]

Tree xylem anatomy is associated with carbon accumulation and wood quality. Increasing nitrogen (N) deposition can cause a significant effect on xylem anatomy, but related information is limited for subtropical broadleaf tree species. A 3-year field N addition experiment, with different N addition approaches (canopy and understory) and addition rates (0, 25, and 50 kg N ha −1  yr −1 ), was performed beginning in 2013 in a subtropical forest of China. N addition effects on xylem tracheid (wall and lumen) size, vessel, and growth of dominant broadleaf species ( Schima superba Gardn . et Champ . and Castanopsis chinensis ( Sprengel ) Hance ) were investigated. The results showed that The effect of N addition on tracheid size was dependent on the tree species and addition approaches. Canopy N addition did not affect the tracheid size of C . chinensis , while both addition approaches increased the tracheid size of S . superba . The vessel size of both species was not affected by N addition. There was no difference in radial growth or other growth-related variables between the control and N-treated trees. These findings indicated that short-term N addition could significantly affect xylem anatomy, but might not influence tree growth. Meanwhile, understory N addition may pose challenges for mechanistic understanding and forest dynamics projection. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eucalyptus dunni is a potential species for pulp production. • E. dunni clones have great genetic variance for growth and wood quality traits. • Wood quality traits presented moderate to high heritability values with high selective accuracies. • Growth and wood quality traits present simple genotypes x environments interaction. • Growth and wood quality traits should be considered in tree breeding for pulp production. Abstract The Eucalyptus dunnii Maiden is an outstanding species for growth and wood quality traits. However, important wood quality traits for pulp and paper production are disregarded in tree breeding. Thus, the present study aimed to estimate the genetic parameters of growth and wood quality traits and establish selection criteria to increase pulp production in E. dunnii clones in different environments. The clonal test of E. dunnii was established in a randomized complete block design with a single-tree-plot in three environments. Growth values were obtained from 3.5-year-old trees. Wood quality values were measured by near-infrared spectroscopy. The phenotype index mean annual pulp increment was calculated using the values of mean annual increment, basic wood density, and pulp yield. A mixed linear model via REML/BLUP was used to obtain the genetic parameters and the rank of genotypic values considering several environments. Results revealed genetic variance for wood quality traits in E. dunnii. Klason Lignin presented high broad-sense heritability; basic wood density, pulp yield, mean annual pulp increment, and mean annual volume increment had moderate broad-sense heritability; and total extractives and diameter at breast height showed low broad-sense heritability. All traits presented high to very high selective accuracy. Simple clones x environments interactions were observed for the tested environments. An elite clone of E. dunnii were better than the commercial control clone for annual pulp increment mean. Therefore, the selection based on growth and wood quality traits is essential for pulp and paper sector. [ABSTRACT FROM AUTHOR]

The world’s wood demand from planted forests is expected to drastically increase in the following decades. Brazil displays very high levels of forest productivity for Pinus and Eucalyptus planted forests. Loblolly pine ( Pinus taeda ) is the most important species in terms of planted forest area in southern Brazil. There, it is mainly used for paper and pulpwood production, but also allows for multi-purpose and high quality wood production. Of particular interest is whether loblolly pine management in southern Brazil comprises a sustainable alternative to world’s wood demand. A promising tool to assess forest sustainability is named emergy synthesis (or emergy accounting). It is a top-down environmental accounting approach set out to assess holistically nature and society’s contributions toward a production process. It converts all forms of energy, materials, and human services into equivalents of one form of energy: Emergy, expressed in solar emjoules (seJ). This study aimed to assess the emergy-based sustainability of a loblolly pine wood production system practiced by a private forest company in southern Brazil (municipality of Rio Negrinho, Santa Catarina State). Data on society’s input (materials, fuels and labor) were provided by the company itself and subsequently checked through field measurements and personal communication with the forestry staff. Nature’s input was segregated into renewable and non-renewable resources, with their estimates being derived from literature information. Renewable natural resources in the form of rainfall comprised 82.4% of total emergy. The organic fraction of soil loss represented the emergy flow of non-renewable natural resources and accounted for 0.85% of total emergy. The remaining 16.75% of total emergy comprised society’s contribution. The loblolly pine system outperformed large-scale, intensively managed agriculture and eucalyptus production systems in Brazil as regards the emergy index of renewability . In relation to planted forests worldwide, this loblolly pine system displayed the lowest transformity , indicating that it was the most efficient system at producing a joule of wood per emergy investment. From the perspective of emergy synthesis, this loblolly pine production system is a feasible alternative to world’s wood demand and to sustainable land use in southern Brazil. While we perceived emergy synthesis to be an important tool to assess forest sustainability, we strongly argue that it should be complemented by other assessment approaches in order to consider, inter alia, short-term adverse impacts on soils and the socioeconomic benefits of providing job opportunities and ecosystem services. [ABSTRACT FROM AUTHOR]

Managed forests in southern U.S. are a potential source of lignocellulosic biomass for biofuel production. Changes in management practices to optimize biomass production may impact the quality of waters draining to nutrient-sensitive waters in coastal plain regions. We investigated shallow groundwater quality effects of intercropping switchgrass ( Panicum virgatum L.) with managed loblolly pine ( Pinus taeda L.) to produce bioenergy feedstock and quality sawtimber in a poorly drained soil of eastern North Carolina, U.S.A. Treatments included PINE (traditional pine production), PSWITCH (pine-switchgrass intercropped), SWITCH (switchgrass monoculture) and REF (mature loblolly pine stand). Each treatment was replicated three times on 0.8 ha plots drained by parallel-open ditches, 1.0–1.2 m deep and 100 m apart. Water samples were collected monthly or more frequently after fertilizer application. Water samples were analyzed for organic nitrogen (ON), ammonium N (NH 4 + - N), and nitrite+nitrate N (NO 3 − + NO 2 − - N), ortohophosphate phosphorus (OP), and total organic carbon (TOC). Overall, PSWITCH did not significantly affect shallow groundwater quality relative to PINE and SWITCH. ON, NO 3 − + NO 2 − - N, and TOC concentrations in PSWITCH, PINE and SWITCH were substantially elevated during the two years after tree harvest and site establishment. The elevated nutrient concentrations at the beginning of the study were likely caused by a combination of rapid organic matter decomposition of the abundant supply of post-harvest residues, warming of exposed soil surfaces and reduction of plant nutrient uptake that can occur after harvesting, and pre-plant fertilization. Nutrient concentrations returned to background levels observed in REF during the third year after harvest. [ABSTRACT FROM AUTHOR]

Provision of adequate environmental enrichment on pig farms is a legal requirement under current EU legislation and also alleviates the risk of tail biting. Wood is an organic alternative where loose bedding, which has been identified as the optimal enrichment, is not possible on fully-slatted floors since it may disrupt the slurry system. The study compared four different wood types (beech ( Fagus sylvatica ), larch ( Larix decidua ), spruce ( Picea sitchensis ), and Scots pine ( Pinus sylvestris L .)) as enrichment, taking into account the qualities of the wood, economic considerations, and effectiveness at reducing damaging behaviours and lesions. A total of 800 tail docked finisher pigs on an Irish commercial farm were used. Eight pens were provided with each wood type (25 pigs/pen), and the study was conducted over 2 replicates in time. In each pen a single wooden post was presented to the pigs in a metal dispenser with two lateral chains during the finisher period (12–22 weeks of age). The rate of wear, moisture content, and hardness of the wood along with lesion scorings and behavioural observation on pigs were monitored. Spruce was consumed more quickly than other wood types in terms of weight loss and reduction in length ( P  < 0.001), resulting in a greater cost per pig. Pigs were observed interacting with the spruce more frequently than the other wood types ( P  < 0.05). Pigs also interacted with the wood more often than the chains in spruce allocated pens ( P  < 0.001). Overall the interaction with wood posts did not decline significantly across time. However, there was no difference in the frequency of harmful behaviours (tail/ear/flank-biting) observed between wood types, and also no difference in the effectiveness of the different types of wood in reducing tail or ear damage. There was a positive correlation between ear lesion and tear-staining scores (r p   = 0.286, P  < 0.01), and between tail lesion and tail posture scores (r p   = 0.206, P  < 0.05). Wood types did not affect visceral condemnation obtained in the slaughterhouse. Wood is a potentially suitable enrichment material, yet the wood species could influence its attractiveness to pigs. [ABSTRACT FROM AUTHOR]

Mixed forest plantations now emerge as an alternative to traditional plantations in the tropics and represent ecological gains associated with production, wood quality and nutrient cycling. Mixed plantations with higher diversity may also be advantageous concerning their use of soil water. To shed light onto water-related issues of mixing Eucalyptus and a high diversity of tropical native trees, we explored the following questions: What is the impact of high diversity mixed plantations of Eucalyptus intercropped with native trees on soil water? How does the mixture affect the physiology of water use in native trees? Firstly, we tested the hypothesis that stands of Eucalyptus mixed with a high diversity of native trees consume less water compared to Eucalyptus monocultures, by measuring the temporal dynamics of soil water. Secondly, we tested how mixing with Eucalyptus affects the hydraulic performance of fast- and slow-growing native species in these forestry systems. This is the first time a large experiment has been implemented to compare the effects of monospecific Eucalyptus plantations, native species mixtures and mixed plantations of Eucalyptus and native species on soil water dynamics under controlled conditions in terms of site, age, soil type, topography and climate. We found that high diversity mixed plantations of Eucalyptus and native trees use less soil water, than Eucalyptus monocultures. However, the soil under the mixtures was drier than in native species stands. The mixing with Eucalyptus affected the hydraulic performance of native species by decreasing the leaf water potential and stomatal conductance of the fast-growing species, suggesting that fast-growing species performance may be especially constrained by competition for water from Eucalyptus . These findings have important implications for forest management and ecological restoration in the tropics. They will help to further develop silvicultural options to adapt to climate change and improve plantation forestry by using mixed plantations for production purposes or rehabilitation of degraded lands. [ABSTRACT FROM AUTHOR]

Sustainable production of wood is one of the main services provided by forest systems. Site productivity in the case of forests is often evaluated through the site quality. However, most of the works addressing the site quality have been done at local or regional scale. In this work, we aim to develop site quality models for five dominant species in Spanish forests ( Fagus sylvatica , Pinus pinaster atlantica , Quercus pyrenaica , Pinus nigra , Pinus sylvestris ) and create site quality maps at a national-scale from these models. First, we develop site quality models using site form (height-diameter relationship) as the reference index and the Spanish National Forest Inventory as dataset. Then, we fit spatial additive models entering physiographic and climatic variables in order to predict the site quality over the whole country. Additionally, we plot site form maps for the five species in order to describe spatial pattern in site quality at a national scale. Altitude and aspect appeared to be fundamental variables in the assessment of site quality. The accuracy of the spatial additive models ranged from 38.2% to 47.9%. The correspondence between the predicted and observed maps of site qualities is clear. Our results provide a tool which could be used by forest managers in land use planning as well as in forest policy decision-making at a national scale. We suggest that this method could be used in other countries and that the maps could be expanded to the European scale to assessing the way in which site quality varies across Europe always considering that the relationships between forest productivity and environmental variables could vary among biogeoclimatic zones. [ABSTRACT FROM AUTHOR]

The study concerns the conservation problem of large scale elements of irregularly degraded archaeological wood being characterized by different susceptibility to agents responsible for wood consolidation and bulking. The conservation effectiveness was established for processes carried out with PEG solutions of different molecular weight with respect to dimensional stabilization, hygroscopic properties and the agent consumption. One of the investigated treatment options had concerned the application of PEG 2000, i.e. poorly studied variant of that type of consolidants. The analysis was performed for wooden elements from a Late Medieval road. The investigated artifacts were characterized by different anatomical structure and each of them included sapwood (SW) and heartwood (HW). Chemical, physical and sorption properties of SW and HW were first determined. A significant difference in the degree of degradation and the content of extractives in SW and HW was observed. The examined artifacts were then impregnated with five different PEG solutions. It was found that the highest anti-shrink efficiency (ASE) was obtained for one-stage PEG 2000 impregnation. The obtained data of sorption experiments showed that all applied impregnation options guaranteed safe exposure of wood in air relative humidity (RH) lower than 80%. Moreover, one-stage impregnation with PEG 2000 assured the lowest equilibrium moisture content ( EMC ) of wood, especially SW, at RH above 80%. [ABSTRACT FROM AUTHOR]

Non-structural carbohydrates provide the carbon and energy for plant growth and survival, being starch one of the main compounds accumulated in woody organs of trees. However, starch quantification in woody tissues is difficult and time consuming. Therefore, we hypothesized that reflectance spectroscopy could provide rapid and low cost methods to quantify carbohydrates in woody tissues. With this aim we analyzed the spectra of trunk tissues from different grapevine species ( Vitis spp.) and results were compared to standard analyses. PLS regression appeared particularly performant for the elaboration and analysis of the collected spectra. This statistical approach produced high correlations with the concentrations of both starch and soluble sugars. To focus on starch detection, a specific on-solid colorimetric reaction was also proposed. Starch-iodine complexation produced significant modifications in spectral features. [ABSTRACT FROM AUTHOR]

The analyses of wood and charcoal recovered from a medieval refuse layer provided information on the use of woody resources between the 10th and 12th century A.D. in the city of Ghent (northern Belgium). During this period, Ghent evolved from a small settlement to a large urban centre. The results show that in the 10th century, the best suited woody taxa were used for both timber and firewood, Quercus sp. being the major wood type in the assemblage of the waterlogged timber remains and Betula sp., Carpinus betulus , Quercus sp. and Fagus sylvatica dominating the charcoal assemblages. By the 11th century, the somewhat less suited wood of Fraxinus excelsior is the most frequently used timber and fuel wood, indicating that the better quality wood taxa had become scarce. During the 12th century, Alnus sp. is the mayor wood type exploited both for fuel wood and construction wood, though this tree provides only very poor quality fuel and timber wood. The evolution in the taxa that have been used for both timber and fuel wood thus shows the overexploitation of woody resources, leading to the shortage of first high quality wood taxa and later also of other tree species that provide medium and low quality timber and fuel wood. [ABSTRACT FROM AUTHOR]

Mixed species stands are on the advance in Central Europe and many recently published studies have reported that they can overyield monocultures in terms of volume growth. However, as forest research has in the past been focused on monocultures, knowledge of how mixed-species stands and monocultures compare in terms of wood quality remains limited. Based on five triplets of fully stocked monocultures and mixed stands of Scots pine ( Pinus sylvestris L.) and European beech ( Fagus sylvatica L.), we analysed whether tree species mixing modifies wood quality and, more precisely, tree ring wood density. From a total of 322 trees we sampled increment cores for the analyses of tree ring width and tree ring wood density using a LIGNOSTATION™. We found that tree ring width of Scots pine was, on average, 14% wider in mixed compared with pure stands. Tree ring width of European beech did not differ between pure and mixed stands. Tree ring wood density was lower in mixed stands compared to pure stands for both Scots pine (−12%) and European beech (−8%). Tree ring wood density and tree ring width were negatively correlated in the case of Scots pine and positively correlated for European beech. When considering tree size and Stand density index, it was found that only tree ring width and mean tree ring wood density of European beech were influenced by stand density. Tree size had a significant effect only on tree ring wood density of European beech. The overall result of larger tree rings of Scots pine in mixed stands and a lower tree ring wood density of both species in mixed stands compared to pure stands was not influenced by stand density or tree size. Based on the measured values of tree ring wood density we conducted estimates of how mixed stands performed in terms of biomass. We found stem biomass to be 8% lower in mixed stands compared to pure stands. Reasons for the revealed differences in tree ring wood density and consequences for, among others, overyielding, carbon storage, and wood quality are discussed. [ABSTRACT FROM AUTHOR]

In burned forestlands, fire scar wounds commonly occur on tree stems as a result of cambial heating. In hardwood forests in particular, wounding can lead to stem decay with the extent of decay being related to scar size and exposure time. Therefore, wound closure rates are important to understand in the context of fire management such that allowing sufficient time for wound closure to occur between fires would enhance wood quality. Conversely, in the context of wildlife management, understanding wound closure rates would improve fire prescriptions needed for creating basal tree cavities as keeping wounds open prior to wound closure could enhance cavity development. The objectives of this study were to quantify growth and wound closure rates of white oaks ( Quercus alba ), one of the most valuable tree species in the central U.S. to both commercial forestry and wildlife. From historically burned, mature, oak-hickory forest site in Missouri, we sampled a wide range of tree sizes, fire scar sizes, and fire scar ages to determine the environmental and tree factors related to closure rates. Dendrochronological techniques were paired with new approaches of digitizing tree rings to capture malformed woundwood areas. The time required for wound closure ranged from 1 to 24 years and was significantly correlated to scar size. Surprisingly, post-fire growth trends were positive following scarring. Growth was positively related to scar and tree size. With this information, we expect that the process of basal wound closure and tree growth can be considered in a quantitative framework and used to guide fire management for wood quality or wildlife tree cavities. [ABSTRACT FROM AUTHOR]

To achieve good quality wood composites, the degree of curing of the adhesive – often an aminoplastic thermosetting resin – is an important factor. Dielectric analysis (DEA) is an established method for characterizing the curing behaviour of coatings. This method is also promising for the online-monitoring of the curing of aminoplastic thermoset resins. By DEA, changes in the curing behaviour as a result of processing conditions (of the composite) can be immediately observed during the production; furthermore DEA enables control and optimisation of the production time. In the present work, DEA cure monitoring was tested in pilot plant scale production of urea-formaldehyde (UF) based particle boards. The measurements were performed during hot-pressing; the pressing times and binder types were varied. The degree of curing was calculated from logarithmic ion viscosity values. Sufficient cross-linking resulted in a significant increase of the ion viscosity. The logarithmic ion viscosity values which are measured at the end of the pressing process were correlated with the transverse tensile strength of the obtained particle boards. [ABSTRACT FROM AUTHOR]

The problem of hole-defect detection in standing trees is solved. An ultrasonic device (Pundit PL-200) was employed to collect ultrasonic signals from various wood specimens both in the lab and field. The collected ultrasonic signals were then processed through the Variational Mode Decomposition algorithm to derive effective features. In order to solve the classification problem more efficiently, the obtained characteristics were then analyzed through PCA to determine the most useful features. Several machine learning algorithms and a one-dimensional convolutional neural network (1D-CNN) were employed to solve a set of classification problems based on data collected from (1) specimens with artificial defects in the lab and (2) billets with natural defects selected from trees harvested at sites in the two states of WA and NSW, Australia. The results demonstrate the effectiveness of the proposed method for classifying wood materials based on their health state, where testing accuracy results of 100% in the lab and at least 92.2% in fields were achieved. The Fine Gaussian SVM was found to perform most effectively on data derived from specimens in the lab and fields. It was also shown that 1D-CNN results were more reliable for generalizing the solution to the classification problem of standing trees in fields. • Contact–ultrasonic testing has been proven effective for wood quality assessment. • A feature extraction procedure is devised based on Variational Mode Decomposition. • Time–frequency features of decomposed signals are informative about wood quality. • Higher IMFs' features are more informative for solving classification problems. • Physics of the problem has been explored from the ML and DP results. [ABSTRACT FROM AUTHOR]

Ordinal problems are those where the label to be predicted from the input data is selected from a group of categories which are naturally ordered. The underlying order is determined by the implicit characteristics of the real problem. They share some characteristics with nominal or standard classification problems but also with regression ones. In the real world, there are many problems of this type in different knowledge areas, such as medical diagnosis, risk prediction or quality control. The latter has gained an increasing interest in the Industry 4.0 scenario. Some weapons manufacturer follow an aesthetic quality control process to determine the quality of the wood used to produce the stock of the weapons they manufacture. This process is an ordinal classification problem that can be automatised using machine learning techniques. Deep learning methods have been widely used for multiples types of tasks including image aesthetic quality control, where convolutional neural networks are the most common alternative, given that they are focused on solving problems where the input data are images. In this work, we propose a new exponential regularised loss function that is usedto improve the classification performance for ordinal problems when using deep neural networks. The proposed methodology is applied to a real-world aesthetic quality control problem. The results and statistical analysis prove that the proposed methodology outperforms other state-of-the-art methods, obtaining very robust results. • Unimodal regularisation for cross-entropy loss using a distribution based on the proposed Lp exponential function. • Comparison with other regularisation methods based on other distributions and the standard nominal method. • Ordinal output scheme based on the cumulative link models with different link functions. • Combined with convolutional neural networks and applied to the aesthetic quality control process to determine the quality of the wood used to manufacture shotgun stocks. [ABSTRACT FROM AUTHOR]

• The effect of late thinning on unmanaged chestnut plantation performance was tested. • The thinning effect on tree growth decreased considerably after 5 years. • The proportion of bifurcated trees was 50 % lower in one plantation 19 years later. • Progressive and frequent thinning improves growth and timber quality. Chestnut (Castanea sativa Mill.) is an interesting species for high-quality timber production. It is well known that the species responds to early thinning, but there is no information on the impact of late interventions. The objective of this study was to assess the effect of a late thinning on the performance of unmanaged adult chestnut plantations in Chile. Future-tree selective thinning and control were compared in adult plantations using a randomized complete block design with three replicates at three sites, Minas, Pillo-Pillo and Pumillahue. Tree growth was evaluated periodically during the first 7 years after thinning in all plantations. Additionally, almost 20 years after the intervention, the Pumillahue plantation was measured for growth and tree shape variables. In this case study, the effect of thinning on tree growth decreased considerably after 5 years, with a maximum DBH increment in the third year after the intervention (45.8 %, 68.6 %, and 42.2 % in Minas, Pillo-Pillo and Pumillahue, respectively). In all plantations, basal area was smaller in the thinned plots in the first years after the intervention, but in Pumillahue, 19 years after thinning, no differences were found among treatments. Height was statistically greater under thinning seven years after the intervention; this effect was also found in Pumillahue plantation 19 years after thinning. Most trees showed high vigor, and were straight and healthy, even in control plots. Late effect of thinning was observed 19 years after thinning on tree shape, with a reduction in the proportion of bifurcated trees from 16 % to 8 %. The results suggest that late thinning is an effective silvicultural intervention to produce high-quality chestnut timber in unmanaged adult plantations. Progressive and frequent thinning should be used to increase growth and improve timber production in chestnut. [ABSTRACT FROM AUTHOR]